Low- and high-molecular weight amorphous polyalphaolefin polymer blends having high melt viscosity, and products thereof

Abstract

A polymer blend having an open time including a high molecular weight average, predominantly atactic flexible polyolefin polymer having a heat of fusion of about 15 to 60 J/g, and a low molecular weight average, atactic polyolefin polymer having a heat of fusion of about 0.1 to 20 J/g, wherein the high molecular weight polymer and low molecular weight polymer are sufficiently miscible to impart a single glass transition temperature to the polymer blend, and the low molecular weight polymer is present in an amount sufficient to impart a melt viscosity of greater than about 8,000 cPs at room temperature and a crystallinity below about 25 J/g to the polymer blend. The invention further includes methods for preparing such polymer blends, and the products produced from the polymer blends, which are useful for hot melt adhesives, asphalt and bitumen applications such as roofing membranes, polymeric modifiers and the like.

What is claimed is: 
     
       1. A polymer blend comprising: a predominantly atactic flexible polyolefin polymer having a high weight average molecular weight of at least about 100,000 and a heat of fusion of about 15 to 60 J/g; and   an atactic polyolefin polymer having a low number average molecular weight of below about 25,000 and a heat of fusion of about 0.1 to 20 J/g, wherein the high molecular weight polymer and low molecular weight polymer are sufficiently miscible to impart a single glass transition temperature and an open time to the polymer blend, and the low molecular weight polymer is present in an amount sufficient to impart a melt viscosity of greater than about 8,000 cPs at room temperature and a crystallinity below about 28 J/g to the polymer blend.   
     
     
       2. The blend of claim 1, wherein the high molecular weight polymer has a heat of fusion between about 18 to 50 J/g and a melt flow rate between about 0.3 g/10 min. to about 100 g/10 min. at 230° C. 
     
     
       3. The blend of claim 2, wherein the heat of fusion is between about 20 to 35 J/g and the melt flow rate is between about 0.4 to 50 g/10 min. 
     
     
       4. The blend of claim 1, wherein the high molecular weight polymer has a weight average molecular weight of between about 150,000 to 200,000 g/mol. 
     
     
       5. The polymer of claim 1, wherein the high molecular weight polymer comprises units of propylene, a copolymer including propylene, or a mixture thereof. 
     
     
       6. The blend of claim 1, wherein the low molecular weight polymer comprises units of ethylene, butene, propylene, or copolymers or a mixture thereof. 
     
     
       7. The blend of claim 1, wherein the low molecular weight polymer has a number average molecular weight of between about 4,000 to 16,000 g/mol. 
     
     
       8. The blend of claim 1, wherein the low molecular weight polymer is present in about 60 to 98 weight percent of the polymer blend. 
     
     
       9. The blend of claim 1, wherein the glass transition temperature is between about -10° C. to -30° C. 
     
     
       10. The blend of claim 1, wherein the melt viscosity is between about 25,000 cPs to 300,000 cPs. 
     
     
       11. The blend of claim 10, wherein the melt viscosity is between about 50,000 to 250,000 cPs. 
     
     
       12. The blend of claim 1, wherein the crystallinity is between about 0.2 to 20 J/g. 
     
     
       13. The blend of claim 1, wherein the open time of the polymer blend is greater than 10 seconds. 
     
     
       14. The blend of claim 1, wherein the open time of the polymer blend is greater than 50 seconds. 
     
     
       15. The blend of claim 1, further comprising an additive of at least one filler, antioxidant, UV stabilizer, pigment, tackifier, wax, or plasticizer. 
     
     
       16. A molded product comprising the polymer blend of claim 1. 
     
     
       17. A roofing component comprising the polymer blend of claim 1. 
     
     
       18. A hot melt adhesive comprising the polymer blend of claim 1. 
     
     
       19. The adhesive of claim 18 disposed on at least one side of a laminar article. 
     
     
       20. A method of preparing a polymer blend comprising combining a high weight average molecular weight, predominantly atactic flexible polyolefin polymer having a heat of fusion of about 15 to 60 J/g and a low number average molecular weight, atactic polyolefin polymer having a heat of fusion of about 0.1 to 20 J/g by heating the high molecular weight polymer and low molecular weight polymer until they are sufficiently miscible to impart a single glass transition temperature and an open time to the polymer blend, wherein the low molecular weight polymer is present in an amount sufficient to impart a melt viscosity of greater than about 8,000 cPs at room temperature and a crystallinity below about 28 J/g to the polymer blend.